【摘要】 分子聚集体表现出单分子所不具备的特有功能,利用吸收光谱对聚集体分子结构特性的研究是理解其电子和能量转移功能的基础。实验中利用紫外-可见分光光度计,检测了叶黄素在乙醇溶液中的单体吸收谱和在1∶1乙醇水溶液中的聚集体吸收谱。并通过对叶黄素单体吸收谱的高斯分解,获得了激发态的振动能级结构参数。理论上采用时间相关函数描述的吸收谱线和Frenkel激子模型,通过模拟单分子吸收光谱,获得了叶黄素分子的激发能、特征模振动频率、Huang-Phys因子等参数。再利用这些参数进行了聚集体分子光谱的模拟,分析了叶黄素聚集体的分子结构影响光谱变化的原因。结果表明,(1)分子间的相互作用是决定吸收光谱峰位移动的主要原因,实验中叶黄素H-聚集体的吸收光谱较单体蓝移了77nm,模拟显示相互作用在2 000cm-1附近;(2)聚集体分子个数越多,聚集协作效应越大,吸收光谱半高宽变小,同时吸收峰进一步蓝移;(3)环境的无序度对吸收光谱的半高宽也存在较大的影响,无序度越大,吸收光谱半高宽越大。实验结果为进一步研究聚集体在生物系统和材料系统中的功能提供了理论依据。更多还原

【Abstract】 Compared with the monomer,aggregate exhibits unique features such as electron and energy transfer which can be understood with the study of absorption spectra.In the experimental the absorption spectra of lutein monomer in ethanol solution and aggregate in 1∶1aqueous ethanol solution are detected by utilizing UV-lVis spectrophotometer.The vibration structure of excited state of lutein monomer is obtained with Gauss decomposition of the absorption spectra.Theoretically,the molecular parameters of excitation energy,vibration frequency of characteristic mode,Huang-Phys factor are calculated by means of simulation of the monomer absorption spectra described by temporal correlation function and Frenkel exciton model.The spectral calculation of the lutein aggregate is conducted by using these parameters and then the factors of the spectral changes affected by the aggregate structure are analyzed.Some conclusions are drawn from the analysis:(1)The absorption peak position of the aggregate is determined mainly by intermolecular interaction.The calculation shows that the interaction is about 2 000cm-1 according77 nm blue shift of absorption spectra from experiment result.(2)With the increase of molecular number of the aggregate the half-width of the absorption spectra decreases and the peak position blue shift slightly due to enhanced cooperation effect.(3)Disorder degree from environment has great influence on half-width for the greater disorder degree the larger half-width.The results of this paper will provide a theoretical reference for the further study of lutein aggregate function in biological and materials systems.更多还原